Wireless systems generally need to control radio frequency (RF) output to ensure transmitted signals are within acceptable regulated limits. For battery powered wireless systems and devices, controlling RF output may increase battery life. There are many other reasons to monitor and control RF output from wireless devices.
Power detectors are used in wireless systems to monitor the power of an RF signal that is output to an antenna. Generally, a power detector produces a direct current (DC) signal that is proportional to the power of the RF signal being sampled. A wireless system may use the DC signal as a measure of the power of the RF signal being transmitted, and thereby make adjustments in order to maintain the output power within system specifications.
Multi-band wireless systems are capable of receiving and transmitting over a wide frequency bandwidth, which may cover a plurality of wireless standards. For example, a multi-band wireless system may be configured to receive and transmit signals associated with the Global Standard for Mobile (GSM) digital system and the Advanced Mobile Phone System (AMPS) analog system. Such a multi-band wireless system generally employs multiple power detectors to monitor the power of the various RF signals output from the wireless system. The use of multiple power detectors in a multi-band wireless system adds to the overall number of components used to realize the system, which affects at least manufacturing costs, system size and may increase the complexity of the system.